Fluid injection apparatus and fabrication method thereof

ABSTRACT

A method for forming a fluid injection apparatus is disclosed. A patterned sacrificial layer is formed overlying a substrate. A electroplate seed layer is formed on the patterned sacrificial layer. A structural layer is formed overlying the electroplate seed layer and the substrate. The structural layer is patterned to form a nozzle. The electroplate seed layer in the nozzle is removed. The sacrificial layer is removed to form a fluid chamber. A protective layer is formed to selectively cover the structural layer and the electroplate seed layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a fluid injection apparatus and fabrication methods thereof, and more particularly to a micro fluid injection apparatus and fabrication methods thereof.

2. Description of the Related Art

Micro fluid injection apparatuses have been widely used in digital apparatuses, such as inkjet printers or others. With the development of micro system engineering, micro fluid injection apparatuses are used in a wide variety of applications, such as fuel injection systems, cell sorting, drug delivery systems, print lithography or micro jet propulsion systems.

FIG. 1 shows a conventional fluid injection apparatus 100. Referring to FIG. 1, a fluid chamber 104 and a manifold 106 are formed in a substrate 102. An electroplate seed layer 108 is formed on the substrate 102, and a structural layer 110 is formed on the electroplate seed layer 108. A portion of the electroplate seed layer 108, is however, exposed, thus, contacting ink in the fluid injection apparatus 100. The electroplate seed layer reacts with the ink, such that the ink deteriorates and the electroplate seed layer 108 peels off.

BRIEF SUMMARY OF INVENTION

A detailed description is given in the following embodiments with reference to the accompanying drawings. These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred illustrative embodiments of the invention, which provide a fluid injection apparatus.

A method for forming a fluid injection apparatus is disclosed. An embodiment of method for forming a fluid injection device comprises forming a patterned sacrificial layer is overlying on a substrate. An electroplate seed layer is formed on the patterned sacrificial layer. A structural layer is formed overlying the electroplate seed layer and the substrate. The structural layer is patterned to form a nozzle. The electroplate seed layer in the nozzle is removed. The sacrificial layer is removed to form a fluid chamber. A protective layer is formed to selectively cover the structural layer and the electroplate seed layer.

The invention further provides a method for forming a fluid injection apparatus. A patterned sacrificial layer is formed overlying a substrate. A electroplate seed layer is formed to at least cover the patterned sacrificial layer. A structural layer is formed overlying the electroplate seed layer and the substrate by electroplating. The structural layer is patterned to form a nozzle. The electroplate seed layer in the nozzle is removed. The substrate is patterned to form a manifold exposing the sacrificial layer. The sacrificial layer is removed to form a fluid chamber. A protective layer is formed to cover the structural layer and the electroplate seed layer by electroless plating, and fills an interface between the structural layer and the electroplate seed layer, wherein the protective layer comprises a nickel layer directly contacting the structural layer and the electroplate seed layer, and a gold layer overlying the nickel layer.

The invention further provides a fluid injection apparatus, comprising a substrate, a structural layer disposed overlying the substrate to form a fluid chamber, wherein the structural layer comprises a nozzle, a electroplate seed layer disposed on an inner sidewall of the fluid chamber, and a protective layer having chemical resistance covering the electroplate seed layer, the structural layer and a interface therebetween.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 shows a conventional fluid injection apparatus.

FIG. 2A˜FIG. 2F show intermediate cross sections of a fluid injection apparatus of an embodiment of the invention.

DETAILED DESCRIPTION OF INVENTION

The following description discloses the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

In this specification, expressions such as “overlying the substrate”, “above the layer”, or “on the film” simply denote a relative positional relationship with respect to the surface of the base layer, regardless of the existence of intermediate layers. Accordingly, these expressions may indicate not only the direct contact of layers, but also, a non-contact state of one or more laminated layers.

FIG. 2A˜FIG. 2F show intermediate cross sections of a fluid injection apparatus of an embodiment of the invention. Referring to FIG. 2A, a substrate 200, such as silicon substrate or glass substrate, is provided. Preferably, the substrate 200 is a silicon substrate. A gate 202, for example comprising polysilicon or metal, is formed on the substrate 200. Next, a first dielectric layer 204, such as silicon oxide, silicon nitride or silicon oxynitride, is formed to cover the gate 202 and a portion of the substrate 200. A first conductive layer 206, such as Al or Cu, is formed on the first dielectric layer 204 and a portion of the substrate 200, wherein a portion of the first conductive layer 206 on opposite sides of the gate 202 respectively acts as a source 207 and a drain 209. The gate 202, the source 207, the drain 209 and other related elements constitute a fluid control device 213 of an embodiment of the invention.

Thereafter, a second dielectric layer 208, such as silicon oxide, silicon nitride or silicon oxynitride, is formed on a portion of the first conductive layer 206, the first dielectric layer 204 and the substrate 200. It is noticed that the second dielectric layer 208 exposes a portion of the first conductive layer 206 and the drain 209 to form a via. A resistance layer 216 is formed to cover a portion of the first conductive layer 206 and the source 207. Next, a second conductive layer 218, such as Al or Cu, is formed on the resistance layer 216, wherein the second conductive layer 218 directly contacts the resistance layer 216. Next, lithography and etching are utilized to pattern the second conductive layer 218 and the resistance layer 216. Thereafter, a portion of the second conductive layer 218 overlying a heating device area is etched to expose a portion of the resistance layer 216. Thus, the resistance layer 216 and the first conductive layer 206 thereunder constitute a heating device 215. A passivation layer 220, such as SiC or SiN, is formed on the second conductive layer 218 and the resistance layer 216, and a metal protective layer 222, such as Ta, is formed on a portion of the resistance layer 216 overlying the heating device 215. Thereafter, the passivation layer 222 is patterned to form a contact pad 217.

Next, dielectric materials, such as oxide, or a macromolecular compound, such as photoresist is formed on the first side 201 of the substrate 200 by, for example deposition or coating, and then patterned by lithography and etching to form a sacrificial layer 224. In this embodiment of the invention, the first side indicates the side where the fluid controlling device 213 is disposed. Preferably, the sacrificial layer 224 is about 2 μm˜100 μm thick.

Referring to FIG. 2B, a electroplate seed layer 226 is formed on the passivation layer 220 and the sacrificial layer 224 by, for example plasma vapor deposition. Preferably, the electroplate seed layer 226 comprises a Ti layer and a Cu layer disposed on the Ti layer. The Ti layer, preferably having a thickness of less than about 1000 Å, is for increasing adhesion between the electroplate seed layer 226 and a layer thereunder. The Cu layer, preferably having a thickness of about 2000 Å˜8000 Å, is for electroplate seeding. Alternatively, in another embodiment of the invention, the electroplate seed layer 226 comprises a Ti layer and a Ni layer disposed on the Ti layer.

Referring to FIG. 2C, photoresist materials are deposited on the electroplate seed layer 226 and the pad 217, and then patterned to form a patterned photoresist layer 228 at a location predetermined to form a nozzle.

Next, a structural layer 230, for example comprising Ni, is formed on the electroplate seed layer 226 by, for example an electroplating process, wherein the portion of the electroplate seed layer 226 covered by the patterned resist layer 228 is not reacted in the electroplating solution during the electroplating process. Thus, the structural layer 230 is formed on a portion of the electroplate seed layer 226 uncovered by the patterned resist layer 228. Preferably, the structural layer 230 is about 5 μm˜100 μm thick.

Referring to FIG. 2D, the patterned photoresist layer 228 is removed by, for example development, stripper or plasma ashing, and a nozzle 232 in the structural layer 230 is formed. Next, a portion of the electroplate seed layer 226 within the nozzle 232 is removed by, for example etching. Note that formation of the nozzle 232 is not limited to the described method. The nozzle 232 can also be formed by patterning the structural layer 230 with lithography and etching. Preferably, the structural layer 230 is about 10 μm˜100 μm thick.

Referring to FIG. 2E, the second side 203 of the substrate 200 is patterned by, for example, photolithography, etching and/or sand blasting to form a manifold 234, wherein the sacrificial layer 224 is exposed. Next, the sacrificial layer 224 is removed through the manifold 234 by, for example etching, to form a fluid chamber 236 connected to the manifold 234. The invention, however, is not limited thereto. The sacrificial layer 234 can be removed through the nozzle 232 before formation of the manifold 234. When the sacrificial layer 234 is formed of macromolecular compound, it can be removed by plasma ashing or stripper.

Next, referring to FIG. 2F, a protective layer 238, such as a stack of Ni layer and a Au layer, is formed to selectively cover the structural layer 230, the exposed electroplate seed layer 226 and/or the interface thereof by electroless plating. Preferably the protective layer 238 is about 3000 Å˜8000 Å thick. Note that the protective layer 238 is required to have good adhesion to structural layer 230 and the electroplate seed layer 226. The process for forming the protective layer 238 can comprise the steps below. First, a nickel layer is formed on the structural layer 230 and the exposed electroplate seed layer 226 by electroless plating. Next, a gold layer is formed on the nickel layer by electroless plating. Thus, the protective layer 238 comprising the nickel layer having good adhesion to the structural layer 230 thereunder, and the gold layer having good chemical resistance is formed.

Since the structural layer 230, the electroplate seed layer 226 and/or the interface thereof are covered by the protective layer 238 having good chemical resistance, the structure of the fluid chamber 236 and the manifold 234 of the fluid injection apparatus are not easily eroded when contacting to a ink for a long duration. Thus, the fluid injection apparatus may have higher stability and increased life.

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

1. A method for forming a fluid injection apparatus, comprising: providing a substrate; forming a patterned sacrificial layer overlying the substrate; forming a electroplate seed layer, at least covering the patterned sacrificial layer; forming a structural layer overlying the electroplate seed layer and the substrate; patterning the structural layer to form a nozzle; removing the electroplate seed layer in the nozzle; removing the sacrificial layer to form a fluid chamber; and forming a protective layer, selectively covering the structural layer and the electroplate seed layer.
 2. The method for forming a fluid injection apparatus as claimed in claim 1, wherein the protective layer has chemical resistance.
 3. The method for forming a fluid injection apparatus as claimed in claim 1, wherein the electroplate seed layer comprising a Ti layer and a Cu layer overlying the Ti layer.
 4. The method for forming a fluid injection apparatus as claimed in claim 1, wherein the protective layer has good adhesion to the structural layer and the electroplate seed layer.
 5. The method for forming a fluid injection apparatus as claimed in claim 1, wherein the protective layer comprises a nickel layer directly contacting the structural layer and the electroplate seed layer, and a gold layer overlying the nickel layer.
 6. The method for forming a fluid injection apparatus as claimed in claim 1, wherein forming a protective layer, selectively covering the structural layer and the electroplate seed layer is accomplished by electroless plating.
 7. The method for forming a fluid injection apparatus as claimed in claim 1, wherein the structural layer comprises nickel.
 8. The method for forming a fluid injection apparatus as claimed in claim 1, further comprising patterning the substrate to form a manifold connecting the fluid chamber.
 9. The method for forming a fluid injection apparatus as claimed in claim 1, before forming a patterned sacrificial layer overlying the substrate, further comprising forming a fluid driving device overlying the substrate.
 10. A method for forming a fluid injection apparatus, comprising: providing a substrate; forming a patterned sacrificial layer overlying the substrate; forming a electroplate seed layer, at least covering the patterned sacrificial layer; electroplating a structural layer overlying the electroplate seed layer and the substrate; patterning the structural layer to form a nozzle; removing the electroplate seed layer in the nozzle; patterning the substrate to form a manifold exposing the sacrificial layer; removing the sacrificial layer to form a fluid chamber; and electroless plating a protective layer, covering the structural layer and the electroplate seed layer, and filling a interface between the structural layer and the electroplate seed layer, wherein the protective layer comprises a nickel layer directly contacting the structural layer and the electroplate seed layer, and a gold layer overlying the nickel layer.
 11. The method for forming a fluid injection apparatus as claimed in claim 10, wherein the patterned sacrificial layer comprises polymer.
 12. The method for forming a fluid injection apparatus as claimed in claim 10, wherein the structural layer comprises nickel.
 13. A fluid injection apparatus, comprising: a substrate; a structural layer disposed overlying the substrate to form a fluid chamber, wherein the structural layer comprises a nozzle; a electroplate seed layer disposed on an inner sidewall of the fluid chamber; and a protective layer having chemical resistance covering the electroplate seed layer, the structural layer and a interface therebetween.
 14. The fluid injection apparatus as claimed in claim 13, wherein the electroplate seed layer comprises a Ti layer and a Cu layer overlying the Ti layer.
 15. The fluid injection apparatus as claimed in claim 13, wherein the protective layer has good adhesion to the structural layer and the electroplate seed layer.
 16. The fluid injection apparatus as claimed in claim 13, wherein the protective layer comprises a nickel layer directly contacting the structural layer and the electroplate seed layer, and a gold layer overlying the nickel layer.
 17. The fluid injection apparatus as claimed in claim 13, wherein the structural layer comprises nickel.
 18. The fluid injection apparatus as claimed in claim 13, wherein the substrate is a silicon substrate.
 19. The fluid injection apparatus as claimed in claim 13, further comprising a fluid driving device disposed overlying the substrate.
 20. The fluid injection apparatus as claimed in claim 13, further comprising a manifold disposed in the substrate, connecting the fluid chamber. 